Respuesta :
Answer: Option (b) is the correct answer.
Explanation:
The elements which have excess or deficiency of electrons will react readily.
Atomic number of Mn is 25 and electronic configuration of [tex]Mn^{2+}[/tex] is [Ar][tex]4s^{0}3d^{5}[/tex]. This configuration is stable.
Atomic number of Cr is 24 and electronic configuration of [tex]Cr[/tex] is [Ar][tex]4s^{1}3d^{5}[/tex]. This configuration is not stable.
Atomic number of Fe is 26 and electronic configuration of [tex]Fe[/tex] is [Ar][tex]4s^{2}3d^{6}[/tex]. This configuration is stable.
Atomic number of Cu is 29 and electronic configuration of [tex]Cu^{2+}[/tex] is [Ar][tex]4s^{0}3d^{9}[/tex]. This configuration is not stable.
Atomic number of Al is 13 and electronic configuration of Al is [tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}[/tex]. This configuration is not stable.
Atomic number of Ba is 56 and electronic configuration of [tex]Ba^{2+}[/tex] is [Kr][tex]4d^{10}5s^{2}5p^{6}[/tex]. This configuration is stable.
Atomic number of Mg is 12 and electronic configuration of [tex]Mg^{2+}[/tex] is [tex]1s^{2}2s^{2}2p^{6}[/tex]. This configuration is stable.
Atomic number of Sn is 50 and electronic configuration of Sn is [Kr][tex]4d^{10}5s^{2}5p^{2}[/tex]. This configuration is stable.
Thus, we can conclude that out of the given options, only Fe and [tex]Cu^{2+}[/tex] reactants would lead to a spontaneous reaction as they have incomplete sub-shells. Therefore, in order to gain stability they will readily react.
